C Program to Check if String is Pangram

// A C Program to check if the given
// string is a pangram or not
#include <stdbool.h>
#include <stdio.h>
#include <string.h>

// Returns true if the string is pangram else false
bool checkPangram(char str[])
{
    // Create a hash table to mark the characters
    // present in the string
    bool mark[26];
    for (int i = 0; i < 26; i++)
        mark[i] = false;

    // For indexing in mark[]
    int index;

    // Traverse all characters
    size_t size = strlen(str);
    for (int i = 0; i < size; i++) {

        // If uppercase character, subtract 'A'
        // to find index.
        if ('A' <= str[i] && str[i] <= 'Z')
            index = str[i] - 'A';

        // If lowercase character, subtract 'a'
        // to find index.
        else if ('a' <= str[i] && str[i] <= 'z')
            index = str[i] - 'a';

        // If this character is other than english
        // lowercase and uppercase characters.
        else
            continue;

        mark[index] = true;
    }

    // Return false if any character is unmarked
    for (int i = 0; i <= 25; i++)
        if (mark[i] == false)
            return (false);

    // If all characters were present
    return (true);
}

// Driver Program to test above functions
int main()
{
    char str[]
        = "The quick brown fox jumps over the lazy dog";
    if (checkPangram(str) == true)
        printf(" %s 
is a pangram", str);
    else
        printf(" %s 
is not a pangram", str);
    return (0);
}

// This code is contributed by Aditya kumar (adityakumar129)